NN-S651WF, NN-S541WF - Panasonic Home Appliance Service Manual (repair manual). Page 15

                               CAUTION
1. High voltage is present at the high voltage terminal of

the High Voltage Inverter (U) including aluminum heat
sink during any cook cycle.

2. It is neither necessary nor advisable to attempt mea-

surement of the high voltage.

3. Before touching any oven components, or wiring,

always unplug the oven from its power source and
discharge the high voltage capacitors.

 NEW. H.V.

(A) Unplug the lead connectors to Power Relay B and verify continuity

of the power relay B 1-2 terminals.

(B) Unplug lead connectors to Primary Latch Switch and Secondary

Latch Switch.

(C) Test the continuity of switches at door opened and closed positions

with ohm meter (low scale).
Normal continuity readings should be as follows.

(A) Unplug lead wires from Inverter Power Supply (U) primary terminals.
(B) Connect test probes of ohm meter to the disconnected leads which

were connected to Inverter Power Supply (U).

(C) Test the continuity of short switch with door opened and closed

positions using lowest scale of the ohm meter.
Normal continuity readings should be as follows.

  Door Closed
   0 

Ω

  (close)

   0 

Ω

  (close)

Primary Latch Switch
Secondary Latch Switch
Power Relay B

Door Closed

∞ Ω

Door Opened

0 

Ω

- 15 -

Continuity checks can only indicate an open filament or a shorted
magnetron. To diagnose for an open filament or shorted
magnetron.

(A) Isolate magnetron from the circuit by disconnecting the leads.
(B) A continuity check across magnetron filament terminals should

indicate one ohm or less.

(C) A continuity check between each filament terminal and magnetron

case should read open.

ANTENNA

COOLING
FIN

MAGNETRON
CASE

HIGHEST
OHM
SCALE

FILAMENT
TERMINALS

04-031M

0

Ω-1Ω

RX1
SCALE

ANTENNA GASKET

HEAT SINK

CHOKE COIL

CURRENT

TRANSFORMER

RESISTOR

SAND BAR

PCB

FILM CAPACITORS

VARISTOR

PRIMARY WINDINGS

SECONDARY

WINDINGS

HIGH VOLTAGE

DIODES

DO NOT TOUCH

DANGER HIGH VOLTAGE

Test if failure codes of H97 or H98 appears by doing the following
procedure.  It is recommended to use an AC line input current
Ampere meter for testing.
Test 1
A.  Place 1 liter of water load into oven cavity.
B.  Unplug 2 pin H.V. lead wire connector CN703 from magnetron
      tube.
C.  Program oven at High power for 1 minute and press start.

1. After approximately 23 seconds, oven stops.
2. During oven operation, input current is approximately 0.5
    to 1A.  If input current is OK, please proceed to test 2.

.

Test 2.

Continued from Test 1
A. Unplug 3 pin connector CN701, CN703 remain unplug.
B. Set oven at High power for 1 minute and start.

1. After approximately 3 seconds, oven stops.
2. During oven operation, input current should be less than
    0.4A.

If both 1 and 2 are OK, the Inverter Power Supply (U) can be
determined OK.

HIGH BOLTAGE
TRANSFORMER

DO NOT TOUCH (HOT/HIGT VOLTAGE)

  Door Opened

  

∞ 

Ω

  (open)

  

∞ 

Ω

  (open)

  

∞ 

Ω  

(open)

Check continuity between switch terminals, by tapping an appropri-
ate pad on the key board.  The contacts assignment of the
respective pads on the key board is as shown in digital programmer
circuit.

 

∞ 

Ω  

(open)

SYMPTOM

Oven stops in 23
seconds after started.

Unplug CN703

INPUT AMPERE

0.5 to 1A

SYMPTOM

Oven stops in 3

seconds after started.

Unplug CN701

INPUT AMPERE

< 0.4A